During the preschool years, children must learn the skills necessary to attend kindergarten "ready to learn," however, many preschool children exhibit problems with attention and activity regulation that interfere with this developmental goal. In fact, 2 to 3% of the preschool population is estimated to meet criteria for Attention-Deficit/Hyperactivity Disorder (AD/HD; Lavigne et al., 1996). Although most children with AD/HD are not diagnosed until elementary school, parents typically report the onset of symptoms during the preschool years (Barkley, 1998). Reporting on a prospective follow-up of hard-to-manage 3-year- old children, Campbell (1987) found that at age 6 about half of the children had persistent overactivity and externalizing behavior problems; this study illustrates that difficult to manage preschool children are at increased risk for AD/HD and externalizing behavior problems, and a significant portion of children with symptoms will improve. Pierce, Ewing, and Campbell (1999) have followed parent-referred hard-to-manage preschool children into early adolescence and found that a high proportion of identified children are later diagnosed with an emotional or behavior disorder. In fact, manifestation of symptoms prior to age 7 is required for diagnosis of AD/HD (American Psychiatric Association [APA], 2000). Thus, parents' anecdotal retrospective reports of symptoms in preschool children and longitudinal research point to the need for early identification and treatment of preschool behavior problems.
However, diagnosing AD/HD among preschool children is especially challenging because of the unique developmental features of early childhood. Features often used to describe a child with AD/HD, such as overactive, aggressive, stubborn, or noncompliant are often characteristic of typically developing preschool children. In addition, other features common to AD/HD such as carelessness, failure to complete tasks, or difficulties following instructions may apply to a number of behavioral issues among preschool children besides AD/HD. Finally, a preschool age child with developmental delay may appear distractible or overactive simply as a result of the child's developmental level, and not because of a condition such as AD/HD. Given the wide variations and changes in behavior that are typical of the preschool developmental period, diagnosing a preschool child with AD/HD, or even at-risk for AD/HD, must include consideration of the consistency, severity, duration and intensity of the target behaviors, as well as the child's overall developmental status.
Behavioral consistency may be particularly important in considering AD/HD among preschool children. For example, Campbell found that those hard-to-manage 3 year olds who showed no short-term change in behavioral symptoms were those children who continued to present with behavior difficulties at age 6. In fact, 67% of those children with no symptom change by age 6 met DSM-III criteria for an externalizing disorder at age 9 (Campbell, 1987; Campbell & Ewing, 1990). Identifying preschool age children at risk for AD/HD is critical so that early preventative intervention may reduce secondary problems.
Children with AD/HD are at risk for developing problems in the areas of learning, behavior, social skills and emotional regulation. Research conducted with school aged children diagnosed with AD/HD has revealed a variety of problems not only with inhibition and persistence but with executive functions, such as organization, planning, goal directed behavior, verbal fluency, problem solving, and the capacity to shift response sets during tasks (Barkley, 1998; Barkley, Grodzinsky & DuPaul, 1992; Goodyear & Hynd, 1992). In addition, children with AD/HD have also been found to be deficient in academic achievement, and are found to be slightly less competent intellectually, often scoring 7 to 15 IQ points below scores of children without AD/HD (Cantwell & Satterfield, 1978; Fischer, Barkley, Edelbrock & Smallish, 1990; Frick et al. …